(a) Field of the Invention
The present invention relates to a plane heating element and a manufacturing method thereof, particularly to the plane heating element that does not generate external electromagnetic waves and a manufacturing method thereof, wherein magnetic fields, formed by the currents that flow through both heat generation wires and input terminal, are eliminated and thus prevent the generation of electromagnetic waves harmful to the human body.
(b) Description of the Related Art
A plane heating element, such as a thermotherapeutic device or an electric blanket, generates heat in a predetermined area and is used for healing or providing warmth while contacting the human body.
Electricity is used as a power source whereby the plane heating element generates heat, and electricity forms a magnetic field and generates electromagnetic waves while a current flows. The formation of a magnetic field and the generation of electromagnetic waves vary in proportion with the magnitude of current. Because it is currently believed that electromagnetic waves cause a number of diseases and severe side effects, regulations on electromagnetic waves discharged from a variety of products are being enacted.
Therefore, although the plane heating element needs to resolve the EMF (Electromagnetic Field Frequency) issue, the conventional type of such element cannot easily achieve this.
A conventional heating element is structured such that the heat generation wires, having a resistance coefficient generated due to a zigzag patterned connection of the input wires, form a series circuit in view of a block entity, but form a parallel circuit within the block.
In this structure, the current flows in one particular direction through the input wires and heating lines. It also flows in one particular direction through the block entity as well as within the block.
As described above, the conventional heating element comprising input electric wires and heat generation wires has a drawback that these lines form magnetic fields when the current flows in a singular direction through both the input wires and the heat generation wires. This results in the generation of EMF harmful to the human body due to the associated magnetic field.